MIKE 21 BW, User Manual, Page: 20 / 196

Getting Started
20 MIKE 21 BW - © DHI
3.4.2 Bathymetry
You have to specify the bathymetry as a type 2 or type 1 data file containing
the water depth covering the model area. Describing the water depth in your
model is one of the most important tasks in the modelling process. A few
hours less spent in setting up the model bathymetry may later on mean extra
days spent in the calibration process.
3.4.3 Sponge layer
In practical for all MIKE 21 BW applications you have to prepare maps (2DH,
dfs2-file) or profile series (1DH, dfs1-file) for efficient absorbtion of short and
long period waves, see section 5.3.11 (Sponge layers).
3.4.4 Porosity layer
Modelling of partial reflection/transmission requires preparation of maps
(2DH) or files (1DH) including porosity layers. An efficient procedure is out-
lined in section 5.3.10 (Porosity layers).
3.4.5 Boundary data
In most cases you will force the model by waves generated inside the model
domain. The
internal wave generation of waves allows you to absorb all
waves leaving the model domain (radiation type boundaries).
3.5 Calibrating and Verifying the Model
3.5.1 Purpose
Having completed all the tasks listed above you are ready to do the first time-
domain wave simulation and to start on the calibration of the model.
The purpose the calibration is to tune the model in order to reproduce
known/measured wave conditions. The calibrated/tuned model is then veri-
fied by running one or more simulations for which measurements are availa-
ble without changing any tuning parameters. This should ensure that
simulations can be made for any wave conditions similar to the calibration
and verification wave conditions with satisfactory results. However, you
should never use simulation results, whether verified or not, without checking
if they are reasonable or not.